Final answer:
In the hammer and ruler gravity experiment, the correct option is A, with the independent variable being the Type of Material, the dependent variable being the Fall Time, and the control variable being the Height of Release. Control variables ensure reliable and valid results by keeping other factors constant.
Step-by-step explanation:
The hammer and ruler gravity experiment aims to test how the release of a ruler (with a hammer attached) affects its fall time. Let's analyze the options provided:
- Independent variable: This is the factor that you change in an experiment to see how it affects the dependent variable. It is what you manipulate.
- Dependent variable: This is the outcome you measure in the experiment; it depends on the changes you make to the independent variable.
- Control variables: These are all the other factors that you keep constant in order to ensure a fair test.
Based on these definitions
- Option A (Correct): Independent: Type of Material; Dependent: Fall Time; Control: Height of Release.
- Option B: Independent: Fall Time; Dependent: Type of Material; Control: Height of Release.
- Option C: Independent: Height of Release; Dependent: Fall Time; Control: Type of Material.
- Option D: Independent: Height of Release; Dependent: Type of Material; Control: Fall Time.
Option A is correct because in the experiment, you would alter the type of material to see how it affects the time it takes for the hammer and ruler to fall, with the height of release being controlled to ensure it's the same for each test. Control variables are crucial because they help ensure that other factors do not affect the dependent variable, leading to more reliable results.